New Cycloadditions in Synthesis

描述：（由申请人提供）介绍独特的化学品 转化可以大大缩短合成途径， 重要的化合物。众所周知，环加成作用特别强大 用于构建高复杂性分子的反应。这一目标 建议开发和使用新环丁二烯的环加成。它将 表明通过以下方式产生的高度官能化的环丁烯： 分子内环丁二烯环加成可以提供一个通用平台， 快速进入复杂的分子系统。特别是，当与 其他关键的转变，分子的复杂性和结构应变， 环加合物为有效构建 中环天然产物，具有有趣的生物活性。 环丁烯环加合物将用于制备环庚烷类化合物 和含环辛脂的产物。分子间和分子内 环丁烯的环丙烷化，然后是选择性的碳-碳键 碎片，将用于有效地产生5-7环系统发现 在许多生物活性天然产品中。类似地，a（2+2） 光环化/片段化策略将提供5-8-5环的通路 系统化学的简明应用对合成 详细描述了二萜如卡尔曼醇。 简而言之，开发环丁二烯的新路线 配合物，研究这些配合物的新型环加成， 证明环加合物在中环合成中的用途将 为构建具有生物学意义的分子提供了更好的机会。

DESCRIPTION: (provided by applicant) The introduction of unique chemical transformations can considerably shorten synthetic pathways toward medicinally important compounds. Cycloadditions are known to be especially powerful reactions for building molecules of high complexity. The objectives of this proposal are to develop and use new cycloadditions of cyclobutadiene. It will be shown that highly functionalized cyclobutenes generated through intramolecular cyclobutadiene cycloadditions can provide a versatile platform for rapid entry into complex molecular systems. In particular, when used with other key transformations, the molecular complexity and structural strain of the cycloadducts offer unique opportunities for the efficient construction of medium ring-containing natural products with intriguing biological activities. The cyclobutene cycloadducts will be used in the preparation of cycloheptanoid and cyclooctanoidcontaining products. Inter- and intramolecular cyclopropanations of the cyclobutenes, followed by selective carbon-carbon bond fragmentations, will be used to generate effectively the 5-7 ring system found in numerous biologically active natural products. Similarly, a (2+2) photocyclization/fragmentaton strategy will provide access to the 5-8-5 ring system. Concise applications of the chemistry toward the synthesis of diterpenes, such as kalmanol, are detailed. In short, the combination of developing new routes toward cyclobutadiene complexes, investigating novel cycloadditions of these complexes, and demonstrating the utility of the cycloadducts in medium ring synthesis will offer improved opportunities for building molecules of biological significance.